In silver halide color photographic light-sensitive materials, it is well known that, with an exposed silver halide serving as an oxidizer, an oxidized aromatic primary amine-series color-developing agent and a coupler are reacted to produce a dye, such as indophenol, indoaniline, indamine, azomethine, phenoxazine, and phenazine, to form an image. In this photographic system, the subtractive color process is used, wherein a color image is formed by yellow, magenta, and cyan dyes.
In order to form a cyan dye image out of these, conventionally, use is made of phenol- or naphthol-series couplers. Since the dyes formed from these couplers have, however, unpreferable absorption in the region from yellow to magenta, they have a problem of making the color reproduction deteriorated, which is earnestly desired to be solved.
As means for solving this problem, heterocyclic compounds described, for example, in U.S. Pat. Nos. 4,728,598, 4,873,183, and EP-A-0249453 (A2) are proposed. However, these couplers have fatal defects in that, for example, they are low in coupling activity and poor in fastness of dyes.
As couplers that overcome these problems, pyrrolotriazole couplers described in U.S. Pat. No. 5,256,526 and EP-0 545 300 are proposed. These couplers are excellent in hue and coupling activity. However, the fastness of the produced dye images is not necessarily satisfactory, and particularly the fastness to light at the area having a low color density is poorer than that of the conventional couplers, and therefore improvement was desired. Further, desirably the whiteness in the white background after the passage of time should be much higher.
Further, since pyrrolotriazole couplers are high in the molecular extinction coefficient of the dyes produced by the reaction with p-phenylenediamine-series color-developing agents, they have the defect that the so-called processing color contamination is high; that is, the oxidized product of the developing agent produced as a result of the silver development in another layer diffused into the red-sensitive layer and reacted with the cyan coupler in the red-sensitive layer, to increase the cyan density.
Further, since pyrrolotriazole couplers are high in the extinction coefficient of the produced dyes, they have the defect that various cyan stains became high due to the reaction of the color-developing agent remaining in the film with the coupler in or after the step of the color-development step at the time of the processing or during the passage of time after the processing.
JP-A-5-150423 ("JP-A" means unexamined published Japanese patent application) describes that the use of a combination of a nitrogen-containing compound, such as a phenidone compound, with a pyrrolotriazole coupler improves color reproduction and fastness. The effect, however, was not satisfactory.
JP-A-6-324446 describes a method of processing a specific silver halide photographic material comprising a silver chloride emulsion in the presence of a specific 1-phenylpyrazolidine-3-one-series compound to attain photographic properties such as sensitivity and .gamma. by high speed development.
As a method of synthesizing .alpha.-alkyl acrylates, a method is known wherein an .alpha.-alkyl acrylate is synthesized from an .alpha.-halofatty acid ester, zinc, and formaldehyde (J. Chem. Soc., 5562 (1965)). However, since the reaction intermediate is an organometal compound, there are such defects as that the moisture in the solvent lowers the yield and the reaction is difficult to control.
Further, there is known a synthesizing method from a fatty acid ester, a strong base, such as lithium diisopropylamide, and formaldehyde (J. Org. Chem., 37, 1256 (1972)). However, in this method, the reaction has to be carried out at an extremely low temperature of as low as -78.degree. C., and as a result the method has many problems as an industrial synthetic method.
Further, Synthesis, 924 (1982) describes a synthesizing method from a phosphorus ylide and formaldehyde. This method, however, has the problems, for example the yield is low.
On the other hand, J. Chem. Soc., 3160 (1961) describes a method of synthesizing .alpha.,.beta.-disubstituted acrylates from an oxalate, a fatty acid ester, benzaldehyde or heptaldehyde. However, the above document does not describe any examples using formaldehyde as the aldehyde.
Further, Helv. Chim. Acta., 1349 (1947) describes a reaction of formaldehyde with an .alpha.-alkyl-.alpha.-alkoxyoxalyl fatty acid ester, similar to the reaction of the present invention. However, according to the method described in the above document, the reaction product is an .alpha.-keto-.beta.-alkoxycarbonyl-.gamma.-lactone, which differs from the present invention. The method described in the document is characterized in that the alkyl group at the .alpha.-position of the fatty acid ester compound, the starting material, is a lower alkyl group.
Further, J. Org. Chem., 42, 1180 (1977) describes a reaction similar to the present invention. However, the above document describes, as examples of esters, cyclic esters (lactones) or phenyl acetate only. These tend to form an anion at the .alpha.-position of the ester.
It does not suggest the present invention directly because, for example, the stability of the intermediate is different.
Further, J. Organomet. Chem., 177, 67 (1979), Fluorine Chem., 56, 295 (1992), and Helv. Chim. Acta., 30, 1495 (1947) describe methods of producing acrylates, but they do not describe the production method of the present invention.
An object of the present invention is to provide a method of synthesizing .alpha.-alkyl acrylates useful as synthetic intermediates for phenidone compounds used in silver halide light-sensitive materials, from inexpensive raw materials, in a high yield, in a short step.
Another object of the present invention is to provide a method of synthesizing .alpha.-alkyl acrylates useful as synthetic intermediates for phenidone compounds that are used in silver halide light-sensitive materials, by a series of continuous reactions without taking out intermediates.
Another object of the present invention is to provide novel phenidone compounds that are used in silver halide light-sensitive materials, from inexpensive raw materials, in a short step, in a high yield, and a method of producing them.
Another object of the present invention is to provide a method of synthesizing phenidones that are used in silver halide light-sensitive materials, by a series of continuous reactions without isolating intermediates.
Another object of the present invention is to provide a silver halide color light-sensitive material excellent in color reproduction and improved in storage stability of the light-sensitive material. Another object of the present invention is to provide a silver halide color light-sensitive material reduced in cyan color contamination at the time of processing. Another object of the present invention is to provide a silver halide color light-sensitive material reduced in cyan stain. Another object of the present invention is to provide a silver halide color light-sensitive material excellent in color-forming property and fastness.